by Fidelindo Lim, M.A., R.N. Minority Nurse Writer
Among the many electrolytes, potassium stands out. It is perhaps the most prescribed electrolyte, followed by magnesium and phosphorous. In cardiac units, it is one of the staple drugs twinned with digoxin. Brand-name orange juice and milk products are now advertised as "potassium rich" to lure not only consumers concerned with heart health, but also the general public.
The health benefits of potassium
When patients ask why they are given potassium, the standard reply is "it's good for your heart." But there is more to it than that. According to the National Council on Potassium in Clinical Practice, evidence supports high-potassium diets can reduce the risk of stroke by combating the effects of sodium.1
When teaching patients about dietary sources of potassium, most nurses stop at bananas. The New England Journal of Medicine published the following categories of excellent potassium sources: Highest Content (>1000 mg [25 mmol] per gram) • Dried figs • Molasses Very High Content (>500 mg [12.5 mmol] per gram) • Dried fruits, nuts • Avocados • Bran cereals, wheat germ • Lima beans High Content (>250 mg [6.2 mmol] per gram) • Vegetables: spinach, tomatoes, broccoli, winter squash, beets, carrots, cauliflower, potatoes • Fruits: bananas, cantaloupe, kiwis, oranges, mangos • Meats: ground beef, steak, pork, veal, lamb
Studies also show reduction in blood pressure after potassium supplementation is three times higher in African Americans than in Caucasians.2 Research suggests that when one's potassium level is below 3.5 mmol/L, supplementation is essential, even in asymptomatic patients with mild-tomoderate hypertension.3 For patients with a history of arrhythmias, the threshold for potassium replacements is higher: 4.0 mmol/L. The Journal of the American Medical Association reports the risk for ventricular fibrillation in acute myocardial infarction is significantly higher in patients with a potassium deficiency (less than 3.9 mmol/L).
The effect of digoxin is enhanced in the presence of hypokalemia. Hypokalemia predisposes a patient to digoxin toxicity by reducing renal clearance and promoting myocardial binding of the drug.4 Maintaining a normal potassium level is important in preventing digoxin toxicity and minimizing the potential side effects.
The daily minimum requirement for potassium in the average adult is 1600–2000 mg (40–50 mEq). It is interesting to note that across racial lines, it is reported that urban whites consume approximately 2500 mg of potassium per day while African Americans take in only 1000 mg per day on average.5
So what can your patients (and you) eat or drink to get an adequate amount of potassium? For starters, eight ounces of orange juice supplies 450 mg of potassium. Milk and vegetable juice (such as V8) are also rich in potassium but, unfortunately, can be loaded with sodium. Additionally, some of these potassium-rich foods can be costly and potentially cause weight gain. But don't limit yourself to bananas; seek diverse foods to supplement your potassium intake.
In the hospital setting, compliance with potassium replacements or therapy can be a challenge. Tablets are better tolerated than the liquid form for patients who do not have any difficulty swallowing. Compliance is also enhanced by the dosing schedule; the more infrequently the patient takes the pill, the better the compliance. Instead of giving 20 mEq BID, you can ask the doctor to order it as 40 mEq once a day as clinical condition allows. In patients taking diuretics, dietary consumption of potassium-rich food is not enough and must be coupled with a potassium supplement.
Mixing potassium liquid with juice or ice makes it easier to swallow. To prevent the occlusion of feeding tubes, give the liquid form to the patient instead of crushing the pills. Lastly, it is important to note that magnesium is an essential cofactor for potassium uptake and maintenance of intracellular potassium level.1 Potassium supplementation works best when the magnesium level is within a normal range (1.5–2.5 mEq/L).
Nurses must be particularly keen on improving potassium intake in vulnerable groups such as the elderly, those who live alone, and persons with disabilities or functional limitations—they are most at risk for low potassium intake.
J. Cohn, P. Kowey, P. Whelton, et al., "New guidelines for potassium replacement in clinical practice," Archive of Internal Medicine 160 (2000): 2429-2436.
P.K. Whelton, J. He, J.A. Cutler, et al., "Effects of oral potassium on blood pressure: meta-analysis of randomized controlled clinical trials," Journal of the American Medical Association 277 (1997):1624-1632.
P.V. Caralis, B.J. Matterson, E. Perez-Stable, "Potassium and diuretic-induced ventricular arrhythmia in ambulatory hypertensive patients," Miner Electrolyte Metabolism 10 (1984): 148-154.
A, Bielecka-Dabrowa, D.P. Mikhailidis, L. Jones, et al., "The meaning of hypokalemia in heart failure," International Journal of Cardiology (2011) doi:10.1016/j.ijcard.2011.06.121
A.K. Mandal, "Hypokalemia and hyperkalemia," Medical Clinics of North America 81 (1997):611-639.